Neutron detection using a Water Cherenkov Detector with pure water and a single PMT

I. SIDELNIK; H. ASOREY; J. JERÓNIMO BLOSTEIN; M. GÓMEZ BERISSO

Bled

Workshop; 9th International Workshop on Ring Imaging Cherenkov Detectors; 2016

UNIVERSIDAD LJUBLJANA

We present the performance of a novel neutron detection technique based on a Water Cherenkov Detector (WCD) employing pure water, an inner coating material actingas a light reflector and diffuser, and a single photomultiplier tube (PMT). The detector employed in this work is part of the Latin American Giant Observatory (LAGO)collaboration, that measures the low energy component of cosmic rays. The experiments presented in this work were performed in presence of 241 AmBe and 252 Cf neutronsources in different neutron moderator and shielding configurations. We show that fast neutrons from 241 AmBe and 241 Cf sources, as well as thermal neutrons from aneutron moderator, having different spectral characteristics, produce essentially the same pulse histogram shape. This characteristic pulse height histogram shape recordedis a clear signature of neutrons with energies lower than ~11 MeV, and was verified in different experimental conditions. Using this experimental data we estimate theneutron detection efficiency for fast neutrons at the level of (15±5)%.